Piston ring gap question

[Jstock85]

I am stock rebuilding a 4.8 to go in an 85 c10. Got the block back with new cam bearings and cleaned up cylinders. I got a set of standard rings which I assume are drop in. The specs say multiply .0040 time 1 inch of the borer the minimum so my question is have I figured correctly...

.0040 x 3.78 = .015

The specs do not specify any difference between the top and 2nd ring so I assume I should gap them the same?

Any information/advice/suggestions will help. Thanks!

[jrusher]

Originally Posted by Jstock85

I am stock rebuilding a 4.8 to go in an 85 c10. Got the block back with new cam bearings and cleaned up cylinders. I got a set of standard rings which I assume are drop in. The specs say multiply .0040 time 1 inch of the borer the minimum so my question is have I figured correctly...

.0040 x 3.78 = .015

The specs do not specify any difference between the top and 2nd ring so I assume I should gap them the same?

Any information/advice/suggestions will help. Thanks!

That sounds about right I would have to check my service manual . Typically top rings are gapped alittle larger 020-.025" depending on boost or nos etc . I just rebuilt my 6 litre not long ago and the rings were gapped on the high end like 025"-030" they were not file fit rings like Ive always ran in other engines BBC/sbc etc . My bores were within spec for wear and i tried two different sets/make of rings no change. I called hastings about the excessive gaps and they told me run them .. So dont be supprized if your gaps are on the high end for clearance

[Jstock85]

Got them from Clevite. I do plan to call them before I install just to make sure. Service manual specs have top ring .009-.017 and second ring .017-.027. I would be within spec on top ring but need to double check on the second ring. Thanks for you help!

[davepl]

That sounds a little narrow to me. I'd want to be 22-25 for safety on an LS motor, as they have been known to butt ring ends. I would WAY rather bleed some minuscule amount of cylinder pressure off than pop the top off a piston!

The fashion/trend on what to do with the second ring seems to change every 5 years, but right now I'm gapping them about the same as the top.

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

[Jstock85]

Thanks dave. According to that chart if I'm rebuilding stock then I should follow the chart for "late model stock" and gap .005 for top ring and .055 for second ring? Is this what you are recommending?

[davepl]

Originally Posted by Jstock85

Thanks dave. According to that chart if I'm rebuilding stock then I should follow the chart for "late model stock" and gap .005 for top ring and .055 for second ring? Is this what you are recommending?

Can't see the chart, but if that's per inch of bore, sounds about right, though I'd go a little more.

0.056 * 4 would give you 0.024

[Willie Makeit]

Originally Posted by davepl

Can't see the chart, but if that's per inch of bore, sounds about right, though I'd go a little more.

0.056 * 4 would give you 0.024

.056 *4 = .224, not .024

i think you mean .006 * 4 = .024

[davepl]

Originally Posted by Willie Makeit

.056 *4 = .224, not .024

i think you mean .006 * 4 = .024

Just checking to see who reads my posts :-)

[Jstock85]

jrusher I called clevite and you are exactly on spec.

20-25
25-30

thanks again!

[jrusher]

Originally Posted by Jstock85

jrusher I called clevite and you are exactly on spec.

20-25
25-30

thanks again!

Right on perfect. After i checked and rechecked my measurements I was almost thinking i should of went up a size on my cylinders but after talking to the ring manufacture they assured me they run these gaps larger on these engines. I hope to fire mine in next couple weeks my swap went sideways when I decided to put a new floor in my cab